Retractable magnetic sheet

ABSTRACT

The invention is a retractable magnetic sheet. A cylindrical rod is biased in a first rotational direction to retract the sheet which is mounted at a first edge to the rod. The sheet is magnetically-receptive, which means magnets can attach to it. The sheet is extended by pulling downwardly against the bias until the ratchet locks the cylindrical rod&#39;s position. Upon pulling downwardly again, the ratchet releases and the rod retracts, winding the sheet up.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates generally to structures to which magnets can be mounted by magnetic attraction between the magnet and the structures.

[0003] 2. Description of the Related Art

[0004] Magnetically receptive structures are well-known as being desirable, because they permit convenient attachment of objects to a surface. For example, magnets can be attached to a household refrigerator door made of steel for the purpose of displaying the magnets themselves or an object partially interposed between the door and the magnet.

[0005] Educational material suppliers have noticed the value of magnetically receptive structures to hold educational materials, such as names, letters, numbers and pictures. Such structures typically take the form of plain panels that can be mounted to walls and conventional chalkboards made of painted steel. More recently, it was discovered that thin steel can be sandwiched between polymer layers to construct a flexible panel that can be cut with scissors and other conventional office tools. This is shown in U.S. Pat. No. 6,235,378 to Lowder, which is incorporated herein by reference. Such panels can be placed in notebooks, on easels, behind or within wallpaper, and in many other places for ease in use.

[0006] Despite the ease in use of the above discussed devices, there is still a need for a conveniently located, compact surface upon which magnets can be mounted.

BRIEF SUMMARY OF THE INVENTION

[0007] The invention is an apparatus for providing a substrate to which a magnet can be attached. The preferred apparatus comprises a cylindrical rod having an axle about which the rod is rotatably mounted. The rod is preferably a circular cylinder. A preferred magnetically receptive sheet has a first edge mounted to the cylindrical rod. A central region of the sheet winds circumferentially around the cylindrical rod and terminates in a second edge opposite the first edge. The second edge is displaceable relative to the cylindrical rod's axle by, for example, grasping the edge by hand and pulling tangentially from the cylindrical rod.

[0008] In the preferred embodiment, a bias is drivingly linked to the cylindrical rod for rotatably biasing the cylindrical rod in a sheet-retracting direction. Furthermore, a ratchet is preferably mounted to the cylindrical rod near the axle, and the ratchet selectively stops rotation of the cylindrical rod in the sheet-retracting direction.

[0009] The invention operates in the following manner. When it is not in use, the sheet is stored by being wrapped essentially completely around the cylindrical rod. When the sheet is desired to be exposed, the free edge of the sheet is grasped by hand and pulled downwardly away from the cylindrical rod. When a desired amount of sheet is exposed, the user stops pulling the sheet and relaxes the downward movement of the sheet while still grasping the sheet. The ratchet catches and stops continued rotation of the cylindrical rod in the sheet-retracting direction. 0Magnets are then placed on the sheet. After the user is finished using the sheet, the sheet is simply pulled downwardly again, thereby releasing the ratchet. This allows the biased cylindrical rod to retract the sheet around the cylindrical rod for storage.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0010]FIG. 1 is a view in perspective illustrating the present invention in a retracted state.

[0011]FIG. 2 is a view in perspective illustrating the present invention in an extended state.

[0012]FIG. 3 is an end view illustrating the preferred ratchet mechanism.

[0013]FIG. 4 is a view in perspective illustrating an alternative embodiment of the present invention.

[0014]FIG. 5 is a view in perspective illustrating another alternative embodiment of the present invention.

[0015]FIG. 6 is a view in perspective illustrating another alternative embodiment of the present invention.

[0016] In describing the preferred embodiment of the invention which is illustrated in the drawings, specific terminology will be resorted to for the sake of clarity. However, it is not intended that the invention be limited to the specific term so selected and it is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar purpose. For example, the word connected or term similar thereto are often used. They are not limited to direct connection, but include connection through other elements where such connection is recognized as being equivalent by those skilled in the art.

DETAILED DESCRIPTION OF THE INVENTION

[0017] The preferred embodiment of the present invention is shown in FIG. 1. The apparatus 10 includes a cylindrical rod 12, which is preferably a circular cylinder approximately one inch in diameter, to which a pair of end caps 14 and 16 are rigidly mounted. The end caps 14 and 16 have axles 18 and 20, respectively, which mount to a fixed structure, for example conventional window shade brackets or similar structures. The rod and end caps of the preferred embodiment are substantially identical to the rod and end caps used with conventional retractable window shades.

[0018] A preferably rectangular sheet 30 has an elongated inner edge 32 (see FIG. 2) mounted longitudinally to a radially outwardly facing surface of the rod 12. The inner edge 32 is preferably glued to the outer surface of the cylindrical rod 12, but can be fastened by other conventional fasteners, such as staples, ultrasonic welds, tape, stitching, etc. The opposite, free edge 34 of the sheet 30 is preferably oriented parallel to the inner edge 32. The region of the sheet 30 between the opposite edges 32 and 34 is wound around the radially outwardly facing surface of the cylindrical rod 12, with each winding being wound around each previous winding of the sheet 30. The flexible sheet 30, which preferably has essentially no “memory” that would cause it to be permanently deformed by being wound around the preferred rod 12 of one inch diameter, thereby conforms generally to the shape of the cylindrical rod 12. A cylindrical rod of greater diameter would be less likely to deform the sheet, and a sheet with significant memory could be used if a larger diameter rod is used. In its retracted position shown in FIG. 1, the apparatus 10 forms an overall size not appreciably larger0 than the rod itself.

[0019] The preferred sheet 30 is made entirely of a magnetically-receptive material, and preferably is made by combining a ferromagnetic powder and an acrylic latex. Alternatively, one or both sides can be coated with paper or any other material that does not interfere with magnetic attraction to the sheet. The sheet 30 can be constructed, for example, in accordance with the teaching of U.S. Pat. No. 5,843,329 and 5,609,788, both to Deetz, which are incorporated herein by reference. Alternatively, the sheet can be made of thin steel with polymer layers on opposite sides in accordance with U.S. Pat. No. 6,235,378 to Lowder, incorporated by reference above. The resulting sheet has two opposing major surfaces to which magnets can attach.

[0020] The axle 18 is rotatably mounted to the corresponding end cap, and a spring is mounted between the axle and the cylindrical rod to bias the cylindrical rod in one direction relative to the axle. Preferably, the cylindrical rod is biased in the direction that tends to wind the sheet 30 around the cylindrical rod 12, which is counterclockwise when viewed from the left end of the rod 12 in FIG. 1. The axle 20 is preferably rigidly mounted to the end cap 16, and is rotatably mounted in a bearing in which the axle 20 rotates. Both axles are mounted in brackets mounted to, for example, a portable frame, a wall, a ceiling, or some other fixed object.

[0021] When the sheet 30 is in the retracted position shown in FIG. 1, it is out of view and compact, thereby saving space. In order to extend the sheet 30 for use, the user grasps the free edge 34 by hand and pulls in a direction away from the cylindrical rod 12 (preferably downwardly along a tangent to the rod) with enough force to overcome the bias that tends to keep the sheet 30 in the retracted position. Thus, the user displaces the free edge 34 away from the cylindrical rod 12, and, as the user continues to pull, exposes an increasing amount of the region of the sheet 30 between the inner edge 32 and the free edge 34. By thus extending the sheet 30, the sheet 30 is exposed to hang vertically by gravitational force, thereby exposing one or both of the major surfaces to which one or more magnets can be attached, as is illustrated by the magnets 36 and 38 in FIG. 2. The sheet can be guided by a track or other structure, if desired, to be positioned other than vertically.

[0022] In the preferred embodiment, the major surfaces of the entire sheet 30 are magnetically receptive. Alternatively, of course, selected sections of the sheet could be made to be magnetically receptive, and other sections of the sheet could be magnetically non-receptive. This could be for the purpose of reducing costs, or for some other reason. Because the sheet 30 is magnetically receptive, meaning magnets (whether permanent or electromagnets) are attracted to the major surfaces thereof, the sheet 30 in its extended position has two convenient major surfaces to which magnets can be attached, such as for teaching or for decoration.

[0023] The preferred sheet 30 remains in the fully extended position shown in FIG. 2, or in a partially open position, by a ratchet mechanism that selectively stops the rotation of the cylindrical rod 12 in the rotational direction in which the cylindrical rod 12 is biased. The preferred ratchet mechanism is substantially identical to the ratchet mechanism used on conventional window shades, and is illustrated in FIG. 3. A circular member 50 has a pair of teeth 51 and 52 on opposite sides of an inner aperture 54 that seats against one of four pawls 56, 57, 58 and 59 formed on the axle 18 that extends through the aperture 54. Of course, other ratchet mechanisms can be substituted as will become apparent to one of ordinary skill upon reading the instant description.

[0024] In an alternative embodiment shown in FIG. 4, a prime mover, such as the electric motor 80, is drivingly linked to a cylindrical rod 82 to rotate the rod 82 for extending and/or retracting the sheet 84. A still further alternative, shown in FIG. 5, includes a manually rotatable cylindrical rod 92, which can be rotated in one direction or the opposition direction by a rope 94 or cord that extends around a pulley 96 drivingly linked to the cylindrical rod 92. By rotating the pulley 96, the drivingly linked cylindrical rod 92 is thereby driven to retract or extend the sheet 98. Alternatively, the cylindrical rod 92 could be hand rotated to extend and retract the sheet 98.

[0025] While the outwardly facing major surface of the sheet 30 is preferably a solid color, such as white, gray, black or any other color, it is also possible to imprint or attach indicia to this surface. Such indicia can include alphanumeric characters, such as letters and numbers, and drawings, such as maps, images of the human skeleton, etc. This permits the user to attach magnets having images of corresponding indicia to the surface to aid instruction. Of course, it is impossible to list all indicia that could be imprinted or attached to the sheet. However, it will become apparent to a person of ordinary skill from the instant description that any indicia that can be imprinted upon other surfaces can be imprinted upon the instant invention's magnetically receptive sheet.

[0026] In another alternative embodiment of the present invention shown in FIG. 6, the orientation of the apparatus is reversed from that of the preferred embodiment. The cylindrical rod 112 is mounted at its free edge 134 to a fixed structure, such as a portable frame or a wall. The opposite edge of the sheet 130 is attached to the cylindrical rod 112 in a manner essentially identical to the preferred embodiment. However, the sheet 130 is unwound from the cylindrical rod 112 by rolling the cylindrical rod 112 downwardly away from the free edge 134. The sheet 130 is retracted by rolling the cylindrical rod 112 upwardly toward the free edge 134. Unwinding and retracting of the sheet 130 can be accomplished manually by hand, or by a motor, bias and ratchet, looped cord, or any other equivalent means for winding and unwinding the cylindrical rod 112.

[0027] In a still further alternative, one or both of the major surfaces of the sheet is a dry-erase material, thereby permitting marking thereon with special-purpose marking pens that subsequently can be erased. Alternatively, one or both of the major surfaces of the sheet can be a surface upon which chalk can write and from which chalk can be erased. Such a sheet has two uses: attachment of magnetic devices thereto and marking thereon.

[0028] Of course, it is also possible to use the present invention as a combination of a magnetic receptive surface and at least one of the following: movie projector screen, window shade and retractable map.

[0029] Additionally, although the preferred cylindrical rod is a circular cylinder, it is possible to instead have an octagonal cylinder or any other polygonal cylinder substituted for the preferred rod. Such polygonal cylinders will likely leave deformations in the sheet where the sheet contacts the intersections of the sides, and therefore are less desirable.

[0030] While certain preferred embodiments of the present invention have been disclosed in detail, it is to be understood that various modifications may be adopted without departing from the spirit of the invention or scope of the following claims. 

1. An apparatus for providing a substrate to which a magnet can be attached, the apparatus comprising: (a) a cylindrical rod having an axle about which said rod is rotatably mounted; and (b) a sheet having a magnetically receptive region, the sheet having a first edge mounted to the cylindrical rod, a central region of the sheet winding circumferentially around the cylindrical rod and terminating in a second edge opposite the first edge, wherein the second edge is displaceable relative to the cylindrical rod's axle.
 2. The apparatus in accordance with claim 1, further comprising means for rotating the cylindrical rod in at least one direction.
 3. The apparatus in accordance with claim 1, further comprising a prime mover drivingly linked to the cylindrical rod for rotating the cylindrical rod in at least one direction.
 4. The apparatus in accordance with claim 1, further comprising a bias drivingly linked to the cylindrical rod for rotatably biasing the cylindrical rod in one direction.
 5. The apparatus in accordance with claim 4, wherein the bias biases the cylindrical rod in a sheet-retracting direction.
 6. The apparatus in accordance with claim 5, wherein the magnetically receptive region of the sheet includes substantially the entire sheet.
 7. The apparatus in accordance with claim 6, further comprising a ratchet mounted to the cylindrical rod near the axle, wherein the ratchet selectively stops rotation of the cylindrical rod in the retracting direction.
 8. The apparatus in accordance with claim 7, wherein the cylindrical rod is a circular cylinder.
 9. The apparatus in accordance with claim 7, wherein the cylindrical rod is an octagonal cylinder.
 10. An apparatus for providing a substrate to which a magnet can be attached, the apparatus comprising: (a) a cylindrical rod having an axle about which the rod is rotatably mounted; (b) a magnetically receptive sheet having a first edge mounted to the cylindrical rod, a central region of the sheet winding circumferentially around the cylindrical rod and terminating in a second edge opposite the first edge, wherein the second edge is displaceable relative to the cylindrical rod's axle; and (c) means for rotating the cylindrical rod to retract the sheet from an extended position.
 11. An apparatus for providing a substrate to which a magnet can be attached, the apparatus comprising: (a) a cylindrical rod having an axle about which the rod is rotatably mounted; (b) a magnetically receptive sheet having a first edge mounted to the cylindrical rod, a central region of the sheet winding circumferentially around the cylindrical rod and terminating in a second edge opposite the first edge, wherein the second edge is displaceable relative to the cylindrical rod's axle; and (c) a bias drivingly linked to the cylindrical rod for rotatably biasing the cylindrical rod in a sheet-retracting direction.
 12. An apparatus for providing a substrate to which a magnet can be attached, the apparatus comprising: (a) a cylindrical rod having an axle about which the rod is rotatably mounted; (b) a magnetically receptive sheet having a first edge mounted to the cylindrical rod, a central region of the sheet winding circumferentially around the cylindrical rod and terminating in a second edge opposite the first edge, wherein the second edge is displaceable relative to the cylindrical rod's axle; (c) a bias drivingly linked to the cylindrical rod for rotatably biasing the cylindrical rod in a sheet-retracting direction; and (d) a ratchet mounted to the cylindrical rod near the axle, wherein the ratchet selectively stops rotation of the cylindrical rod in the sheet-retracting direction.
 13. The apparatus in accordance with claim 12, wherein the cylindrical rod is a circular cylinder.
 14. An apparatus for providing a substrate to which a magnet can be attached, the apparatus comprising: (a) a rotatable cylindrical rod having an axis of rotation; (b) a sheet having a magnetically receptive region, the sheet having a first edge mounted to the cylindrical rod, a central region of the sheet winding circumferentially around the cylindrical rod and terminating in a second edge opposite the first edge, wherein the second edge and the cylindrical rod's axis of rotation relatively are displaceable.
 15. An apparatus for providing a substrate to which a magnet can be attached, the apparatus comprising: (a) a cylindrical rod having an axle about which the rod is rotatably mounted; (b) a magnetically receptive sheet having a first edge mounted to the cylindrical rod, a central region of the sheet winding circumferentially around the cylindrical rod and terminating in a second edge opposite the first edge, wherein the second edge is displaceable relative to the cylindrical rod's axle; (c) a bias drivingly linked to the cylindrical rod for rotatably biasing the cylindrical rod in a sheet-retracting direction; and (d) a magnet removably mounted to a major surface of the sheet. 